That's an extreme stretch. She's definitely a stubborn arsehole, and has a bunch of issues due to her upbringing, but I really don't feel "psychopath" or "narcissist" really apply to her. She likes people who fight her to much to be a narcissist, and while there are moments she comes across as a psychopath, there's enough hints that's just part of her front.
My 2 Cents. Make of it what you will.....
Quinn shows signs of being morally evil. People that get satisfaction, happiness, etc from the misfortunes of other people are considered evil by psychology. She does the above, and the satisfaction she gets from simply messing with people strengthens that likelihood.
Vinny showed in a previous episode he was willing to do things normal college kids do, such as join a frat, go through Hell Week, and be part of the guys. His motivations for getting into the drug world aren't known, and while pulling a gun and dealing drugs are bad things, is he closer to an Average Joe or a Super Villian? Is Vinny a person that thoroughly enjoys his business to the point that he exacts that joy from the misery he inflicts on others? We don't know enough about him to confirm or deny that notion. He likely has chosen a terrible profession and operates in that profession as any man operating a business might. Why he chose that route and quit college isn't known either. Does he twiddle his thumbs and cackle as a bolt of lightning strikes behind him when he sentences a hit or a beating, etc to someone that didn't pay up? Or does he do so after just getting done talking to a friend about a grocery list?
We do know that Quinn enjoys screwing with people as a way to entertain herself. It is something she does for pleasure and fun, which is a much more evil act than doing evil acts out of necessity for a business/way of life.
The primary motivator for a person like Vinny to enter into an underground business is greed and ambition. Greed is evil, but it's not known if he is evil because he's greedy and ambitious. Their greed leads to evil acts, but the punishments are necessities to drug lords, as letting a person off with a warning or demanding a simple repayment, would only lessen his credibility in the underground world and lead to further issues. While that isn't an excuse. as killing or beating people up or even threatening them with a gun is wrong, but it helps us understand the difference between messing with people for pleasure and messing with them for business. A distinction that helps us recognize his actions as evil, but not necessarily his person.
Does the person specifically do what they do to cause people harm, or is it a byproduct of the career they've chosen? The deeds are evil and that can lead to collateral damage. Either way, Vinny is a deeply troubled person with irrational responses. But is that a byproduct of being evil, or potentially having an anger problem leading him to react irrationally.
Tommy seems to be a spoiled brat that has gotten anything he's wanted in life without working for it. He likely has never dealt with any severe problems in life. He is simply spoiled and stupid and likely has an inferiority complex.